CHICAGO -- Abraham Lincoln has been dead for 142 years, but he still manages to make medical headlines, this time from doctors who say he had a bad case of smallpox when he delivered the Gettysburg Address.

Physicians in Baltimore said last week that Lincoln might have survived being shot if today's medical technology had existed in 1865. Last year, University of Minnesota researchers suggested that a genetic nerve disorder rather than the long-speculated Marfan syndrome might have caused his clunky gait.

"If you play doctor, it's difficult to shut down the diagnostic process" when reading about historical figures, said Dr. Armond Goldman, an immunology specialist and professor emeritus at the University of Texas Medical Branch in Galveston. He and a colleague "diagnosed" serious smallpox in Lincoln after scouring historical documents, biographies and old newspaper clippings.

Their report appears in May's Journal of Medical Biography.

"Lincoln is such a famous figure in American life that people are just automatically drawn to him," Goldman said.

Heart illness, eye problems and depression are among other ailments modern-day doctors have investigated in the 16th president. But smallpox is the one that might come as the biggest surprise to the general public, especially if Lincoln had it when he spoke at Gettysburg.

According to Goldman and co-author Dr. Frank Schmalstieg, Lincoln fell ill Nov. 18, the day before giving the speech in Pennsylvania. When Lincoln arrived at the battlefield to dedicate a cemetery for the fallen soldiers, he was weak, dizzy, and his face "had a ghastly color," according to the report.

On the train back to Washington that evening, Lincoln was feverish and had severe headaches. Then he developed back pains, exhaustion and a widespread scarlet rash that turned blister-like. A servant who tended to Lincoln during the three-week illness later developed smallpox and died in January 1864.

The smallpox theory isn't news to many historians, although some say documents suggest Lincoln had a mild form of the disease.

"In historians' minds, it really doesn't matter too much if he was suffering from the slightly milder case or more serious disease," said Kim Bauer, head of the Lincoln Heritage Project in Decatur. "It was still severe enough that people were still concerned."

Rodney Davis, a Lincoln historian at Illinois' Knox College, said people who don't read Lincoln biographies may not know about his smallpox, but "it's not anything that's ever been suppressed. It's just never been all that significant given the highlights of his career."

Citing an autobiography of J.M.T. Finney Jr., an early 20th century surgeon, the report says a physician summoned by Lincoln's personal doctor diagnosed a mild form of smallpox. Upon hearing the contagious diagnosis, the report says, Lincoln joked that while he was constantly hounded by people who wanted something from him, '"For once in my life as President, I find myself in a position to give everybody something!'"

The authors in the May journal argue that Lincoln's symptoms suggest it was instead full-blown smallpox, which was common at the time and killed many Civil War soldiers despite an early vaccine.

It is unclear if Lincoln was ever vaccinated, the authors wrote. There are few descriptions of his disease, and notes from his personal physician that might shed more light have not been found, they said.

If Lincoln had smallpox, it's unclear where he got it. Goldman and Schmalstieg suggest it might have been from Lincoln's 10-year-old son, Tad, who was bedridden with a feverish illness and rash around the same time. But that is speculation since details of what sickened Tad are not known, the authors said.

Dr. William Schaffner, an infectious disease specialist at Vanderbilt University who scanned the report and just finished reading a Lincoln biography, said he's skeptical that Lincoln had any form of smallpox.

"I find the argument entrancing, but I don't find it convincing," Schaffner said.

Lincoln's symptoms could have been chickenpox or scarlet fever, a strep infection that also can cause a blister-like rash, Schaffner said.

"Here we are in the 21st century and we're trying to know and understand and read language of physicians in the 1850s," Schaffner said.